This invention relates to an improved mold for continuously casting metals and more particularly to a mold which has a friction-reducing material interposed between the copper liner and the steel backing plate to minimize thermal restraint.
A conventional continuous-casting mold is double-walled open-ended tube of various cross sections. The inner wall or liner of the mold usually is copper, but may be other materials which exhibit high thermal conductivity. The outer wall of the mold is usually steel which serves several distinct functions. First, it is the structural member which, because of its stiffness and strength, is primarily responsible for maintaining the liner in its original nondistorted shape. Secondly, it serves as a jacket for water that flows between it and the liner for cooling the liner and assisting in the solidification of the casting.
In conventional mold construction, the liner and the backing plate are secured together with studs or bolts which are connected to the liner and protrude through holes in the backing plate. The nuts or stud heads are tightened with a predetermined torque.
When molten metal is poured through the liner, the temperature of the liner increases much more than the temperature of backing plates. The liner tends to distort, bowing inwardly with respect to the backing plates. Subsequently, when the mold cools, the liner not only returns to its original configuration, but may actually bow outwardly if it had been heated to a sufficiently high temperature. These distortions in the liner produce relative movement between the liner and backing plates. If the liner is restrained against relative movement, permanent distortion and undesirable thermal stresses result.
It is, therefore, the primary object of my invention to provide an improved continuous-casting mold which has means for reducing the coefficient of friction significantly from the coefficient of friction which results from copper bearing against steel.
Another object of my invention is to provide a continuous-casting mold in which there is minimal restraint against thermal expansion of the liner.
Still another object of my invention is to provide a method and means for reducing the coefficient of friction by interposing between the backing plates and liner a friction-reducing material that may be applied by spraying, or in the form of sheets or tape.
These and various other objects and advantages of my invention will become apparent from the following detailed description when taken in conjunction with the attached drawings.